This invention is directed to a spray gun for spraying a component system. The spray gun has a chamber with a piston located in the chamber and one or more hollow control rods attached to the piston. The hollow control rods each have an gas passage leading from one end of the control rod to the other. A first end of the control rod fits into a seat which serves as a valve for dispensing of a spray component. The piston includes an gas passage the end of which also sits into a seat. For better dispersion and ejection of the spray component from the spray gun, when the piston is retracted for spraying the spray component, the gas passage through the piston is open, allowing gas to flow through the piston and through the control rods so as to concurrently eject gas along with ejection of the spray component.
Numerous spray gun systems are known. These are utilized to dispense certain liquid components in a fine, even spray. For dispensing a single component, as for instance paint, a relatively unsophisticated, simple spray gun can be utilized since the paint stays liquid for a relatively long period of time.
In other, more sophisticated spray component systems, known as plural component systems, two or more components are concurrently sprayed from the gun. These components are mixed with one another and polymerize in a relatively short period of time, forming a polymerized solid. In these types of systems, consideration must be given to maintaining the separation of the components within the spray gun and for providing instantaneous cleaning for removing any mixed components from the spray gun to prevent these components from polymerizing within the spray gun. If the components do in fact polymerize within the spray gun itself, it is an arduous task to clean the spray gun. Cleaning of such a plugged spray gun requires disassembly of the spray gun and, in certain instances, replacement of certain blocked components, such as small nozzle orifices and the like.
One of the most useful plural component systems is a fiberglass system. In such a system a first component would be composed of a resin and a second component composed of a catalyst. These two components are sprayed from the spray gun and mixed in the spray directly in front of the spray gun. As soon as the components are mixed a reaction starts, polymerizing the resin into a solid, coherent mass.
These fiberglass spray guns can be augmented by including a chopper assembly which is capable of chopping up a fiberglass roving and concurrently spraying short segments of fiberglass into the spray pattern of the resin and catalyst ejected from the resin and catalyst nozzles. The composite mixture, the fiberglass strands embedded in the catalyzed resin, is directed to a surface for polymerization on the surface to form the fiberglass article.
In U.S. Pat. Nos. 3,947,962; 3,986,672 and 4,325,531, I, along with a co-inventor, described certain spray gun systems and/or chopper assemblies for spraying plural components, as for instance, a fiberglass system. Further, in U.S. Pat. No. 4,583,691 I described a clean-out system for these plural component spray guns.
Of the above spray gun systems, the system described in U.S. Pat. No. 3,986,672 would be normally used for spraying a resin and a catalyst to form a fiberglass. This would be utilized in conjunction with a chopper assembly, as for instance the chopper assembly shown in U.S. Pat. No. 3,947,962. For spraying other component systems, as for instance polyurethane systems or the like, the spray gun of the above mentioned U.S. Pat. No. 4,3425,513 would be most useful. Each of these patents describes spray guns which have very useful features incorporated therein.
The spray gun of U.S. Pat. No. 3,986,672 utilizes component mixing external of the nozzles of the gun with mixing of these components totally dependent upon the spray nozzles of this gun. The spray gun of U.S. Pat. No. 4,325,531 utilizes mixing within the body of the gun itself; however, the material ejected from this gun is not ejected in a spray pattern which would be useful for fiberglass systems, but in fact is ejected in a pattern useful for forming solid urethane foams or air entrained urethane foams. The spray pattern which is emitted from the spray gun of U.S. Pat. No. 4,325,513 is not useful for entraining chopped fiberglass strands therein for forming fiberglass.
In view of the above, it is evident that there exists a need for new and improved spray guns for spraying component systems and the like.